Method of forming detachable drill bit shanks



Jan. 3, 1939. c. E. COOK 2,142,239

METHOD OF FORMING DETACHABLE DRILL BIT SHANKS Filed Sept. 23, 1937 2 Sheets-Sheet 1 FIG. .1.

\ Inuantu'n' d B- E. CDUK B A 4 gi'mwwmm Jan. 3, 1939. Q K 2,142,239

METHOD OF FORMING DETACHABLE DRILL BIT SHANKS Filed Sept. 25, 1937 2 Sheets-Sheet 2 k 3 i Q j E ;l;

3; 7 FILE- E ////7 Inuarrb or B. B. EEIDK Patented Jan. 3, 1939 UNITED STATES PATENT orncs METHOD OF FORMING DETACHABLE DRILL BIT SHANKS Application September 23, 1937, Serial No. 165,238

8 Claims.

My invention relates to improvements in methods of forming detachable drill bit shanksand an object of my invention is to devise a method for forming such shanks wherein no metal is removed from the drill' steel stck from which the shank is fabricated thus resulting in avery considerable economy in the consumption of steel.

A further object is toevolve a method wherein no special. machines are necessary for". forming the steel stock into a shank and consequently no specially trained operators are required, thus efiecting additional economy in the cost of production, which method is further rendered even more economical due to the minimum number of heats and operations necessary, and due to the fact that no annealing of the shank is necessary as theend thereof for connection to the bit is formed by a forging operation instead of by machining as is the orthodox practice.

A still further object is to devise a method which may alternatively be employed to recondition damaged or worn shanks.

My method is particularly adaptable for forming the detachable bit shanks of the construction described in United States Patent No. 2,030,576, issued February 11, 1936, whereinthe bit is connected to the shank by a .dovetail tongue received into a dovetail slot in the shank end, and it is the fabricating of such construction of shank that I have illustrated in the accompanying drawings in whicb:-

Fig. 1 represents a side elevation of a drill steel stock showing a grinding wheel applied thereto for grinding the end of the stock perpendicularly to the longitudinal axis thereof.

Fig. 2 is a side elevation of the stock referred to in Fig. 1 illustrating-it held between the upper and lower portions of a divided clamping die (shown in section) and its end about to be upset by a reciprocable dolly (shown in elevation).

Fig. 3 is a similar view to Fig. 2 only showing the dollying operation on the shank completed with the end'of the shank upset into enlarged circular cross-section corresponding to that of the larger end of the interior of the divided die.

Fig. 4 is a cross-sectional view taken through the line 4-4 (Fig. 3).

Fig. 5 ma cross-sectional view taken through the line 5-5 (Fig. 3)

Fig. 6 is a similar view to Figs. 2 and 3 only showing a further dolly replacing that above referred to and having formed a straight walled slot in the end of the stock.

Fig. 7 is also a similar view to Figs. 2, 3 and 6 u only showing a still further dolly having a re- (Cl. wa -a) I movable head with a dovetail shaped tip having formed the'straight walled slot in the end 0! the stock or shank as it'may now be termed into one of dovetail shape cross-section.

Fig. 8 is a perspective det'ailoi the end of the dolly shown in Fig. 6, and

Fig. 9-ls a similar view of the dolly of Fig. 7.

Like characters of reference indicate corresponding parts in the difierent views of the drawings.

In carrying out my method, as illustrated, I first square oif the end of thevstock A. I then place it between the upper and lower parts I and 2 of a divided clamping die, which parts are respectively attached to the ram 3 and lower die holding block 4 of a standard drill steel sharpener. With the stock A previously heated held firmly in place between the parts I and 2 of the divided die, I submit the end to the dollying op- ,eration of the reciprocable flat faced dolly S which may have a pointed centering tine 6 centrally disposed on its" flat face, it being understood that the dolly 5 is mounted in the dollying attachment (not shown) of the drill steel sharpener with its longitudinal axis coincident with the longitudinal axis of the stock A.

Such dollying operation by the flat faced dolly 5 upsets the heated squared end of the stock A forcing it into the enlarged end I, l of the interior of the divided die and causing it to iill the same as illustrated in Figs. 3 and 5 of the drawings wherein it assumes an enlarged form of circular cross-section B corresponding to the cross-sectional shape of the interior 1, l of such end of the divided die.

Thus the stock A is forged into a drill shank with an enlarged circular end. It now remains to form a transverse dovetail slot in the end of the shank to receive the dovetail connecting tongue of the detachable bit.

The fiat faced dolly 5 of Fig. 2 is now replaced by another dolly ,9" (illustrated in Figs. 8 and 8) having a raised diametrically disposed rib II with straight side walls and the enlarged end B of the shank is submitted to a further dollying operation wherein a transverse slot II with straight side walls is formed in the shank end B as illustrated in Fig. 6 of the drawings.

The shank is now removed from the divided clamping die and is reheated being subsequently placed again in the die and firmly clamped therein. A dolly 12 (Figs. 7 and 9) is subs ituted for the dolly 9 in the dollying attachment of the drill sharpener. Such dolly I2 is constructed in two pieces with its removable head It having a.

transverse rib I 4 of dovetail cross-section formed on its exposed end, the form of the rib being that of the slot in the shank which it is desired to form. The removable head It is inserted into a bore I! in the end of the dolly proper l2 which is itself secured in the dollying attachment.

The dolly I2 is now adjusted so that the rib I4 is inserted into the straight walled slot ll of the shank end and such end is again doliied by such dolly with the result that the straight walled slot ll iii-forged into a slot-l8 of dovetail crosssection as illustrated in Fig. 7 of the drawings which is the ultimate and required shape thereof.

The dolly proper i2 is then removed leaving the removable head I3 on the shank end. The shank is now removed from the divided die and the removable head, which is held to the shank end by the rib I being disposed in the slot i6, is tapped transversely wherein it is detached from the shank end.

A method of forming detachable drill bit shanks of the type above described possesses the advantage that it is fabricated entirely by forging operations in a drill sharpener as usually employed in mines where such drills are primarily used. No expensive machines are required such as is the case with conventional methods which entail machining operations. Furthermore, niy method entails no wastage of steel such as conventional methods involving machining do, and there is a saving in heating and operations as well as in labour costs.

Consequently my method is particularly appli cable for use in the steel shops of minesio'r fabricating new drill shanks ofthe type s'et'forth, as well as for reconditioning -used shanks whic have become damaged or worn.

Although I have described and illustrated my method as being particularly adaptable td iforming detachable drill bit shanks of the type referred to in the above United States patent, it

will be understood that such method may be employed for forming other types of detachable drill bit shanks by changing the design of the dollies used.

What I claim as my invention is:

1. In a method of forming detachable drill bit shanks of the type in which the shank end is provided with a transverse dovetail slot for the reception of .the connecting dovetail tongue of a detachable bit, the steps which consist in clamping a previously heated drill steel stock between the parts of a divided die in a drill sharpener, said die having one end of its interior enlarged and of circular cross-section, by a dollying operation of the. dollying attachment of the drill sharpener upsetting the end of the stock disposed .in the die sc-that it fills the enlarged end of the die and assumes its shape wherein a drill shank with an enlarged circular end is constituted, by a further dollying operation forging a transverse straight walled slot in the end face 'of the enlarged end of the shank, and by a still further dollying operation forging such straight walled slot into a slot of dovetail cross-section.

2. In a method of forming detachable drill bit shanks of the type in which the shank end is provided with a transverse dovetail slot for the reception of the connecting dovetail tongue of a detachable bit, the steps which consist in clamping a previously heated drill steel stock between the parts of a divided die in a drill sharpener, said die having one end of its interior enlarged and of circular cross-section, by a flat faced dolly actuated by the dollying attachment of the drill sharpener dollying the end of the stock disposed within the die wherein it is upset and fills the enlarged end of the die wherein a drill shank with an enlarged circular end is constituted, subsequently by a dolly having a diametrical rib with straight side walls on its end face dollying the enlarged end of the shank in the die wherein a straight walled slot is forged therein, and finally by a dolly having a diametrical rib of dovetail cross-section dollying the enlarged and of the shank whereby the straight walled slot therein is forged into a slot of dovetail cross-section.

3. A method as claimed in claim 2 wherein the shank is removed from the die after the straight walled slot has been forged in the enlarged end thereof, is then reheated and again clamped in the die prior to the final dollying operation.

4. A method of forming detachable drill bit shanks of the type in which the shank end is provided with a transverse dovetail slot for the N reception of the connecting dovetail tongue of a detachable bit which consists in clamping a preheated drill steel stock having its end previously squared off perpendicularly to its longitudinal axis between the parts of a divided die having one end of its interior enlarged and of circular crosssection in a drill sharpener, by a flat faced dolly dollying the end of the stock whereby it is upset and fills the enlarged end of the interior of the die wherein a drill shank with an enlarged circular end is constituted, by a dolly having a diametrical straight walled rib on its end face dollying the enlarged end of the shank in the die wherein a straight walled slot is forged therein. removing the shank from the die, reheating it, firmly clamping it in the die again, by a dolly having a diametrical rib of dovetail cross-section on its end face inserted in the straight walled slot in the enlarged end of the shank dollying such shank end to forge the straight walled slot into a slot of dovetail cross-section.

5. A method as claimed in claim 4 wherein the dovetail rib on the last mentioned dolly is provided on a removable head of the dolly proper, removing such dolly proper from its head after the final dollying operation leaving the head attached to the shank end by means of the dovetail rib, removing the shank from the die and subsequently tapping the head transversely whereby its dovetail rib is displaced from the dovetail slot in the shank end.

6. In a method of forming detachable drill bit shanks of the type in which the shank end is provided with a transverse dovetail slot for the reception of the connecting dovetail tongue of a detachable bit, the steps which consist in dollying the end of an unfinished shank having a straight walled diametrical slot therein with a dolly having a removable head with a diametrical rib of dovetail cross-section on its exposed end face by inserting said rib into the straight walled slot in the shank end, whereby the straight walled slot is forged into a slot of dovetail cross-section extending from one side to the opposite side of the shank wall, removing the dolly leaving the removable head attached to the shank end by means of the dovetail rib in the dovetail slot, and tapping the head transversely to displace its dovetail rib from the dovetail slot in the shank end.

7. A method of forming detachable drill bit shanks of the type in which the shank end is provided with a transverse dovetail slot for the reception of the connecting dovetail tongue of a detachable bit which consists in first forging a straight walled diametrical slot in the shank end extending from one side to the other side of the shank wall by means oi! a dolly having a straight walled diametrically extending slot forming rib, subsequently subjecting the shank end to the dollying action of another dolly lQving a diametrical rib of dovetail cross-section inserted into the straight walled slot in the shank end where by such straight walled slot is iorged into a slot of dovetail cross-section, and finally moving the dolly provided with the diametrical rib oi dovetail cross-section transversely to detach it from the formed slot of dovetail cross-section in the shank end.

8. In a method of forming detachable drill bit shanks of the type in which the shank end is provided with a transverse dovetail slot for the reception oi the connecting dovetail tongue of a detachable bit, the steps which consist in forging the end of an unfinished shank having a straight walled diametrical slot therein extending from one side to the other side of the shank wall by means of a dolly having a diametrical rib of dovetail cross-section inserted into the straight walled slot whereby such straight walled slot is forged into a slot of dovetail cross-section, and subsequently moving the dolly transversely to detach its rib of dovetail cross-section from the formed slot of dovetail cross-section in the shank end.

CHARLES EDWARD COOK. 

